Bastion
According to the dictionary, a bastion is ``a fortified area or
position'', or ``something that is considered a stronghold.'' It's a
suitable name for this module, which provides a way to forbid access
to certain attributes of an object. It must always be used with the
rexec module, in order to allow restricted-mode programs access
to certain safe attributes of an object, while denying access to
other, unsafe attributes.
If present, filter must be a function that accepts a string
containing an attribute name, and returns true if access to that
attribute will be permitted; if filter returns false, the access
is denied. The default filter denies access to any function beginning
with an underscore (_). The bastion's string representation
will be <Bastion for name> if a value for
name is provided; otherwise, repr(object) will be used.
class, if present, would be a subclass of BastionClass;
see the code in `bastion.py' for the details. Overriding the
default BastionClass will rarely be required.